Daniil Ponomarenko, PhD at Nikhef will defend his thesis Monday 25 November 2024 at 14.30 at the Radboud University.
“The W boson production at ATLAS experiment: Drell-Yan angular distributions for probing hard QCD”
he Standard Model of particle physics, while remarkably successful, fails to explain several unresolved phenomena, such as dark matter, dark energy, and baryon asymmetry, motivating the search for new physics beyond it. Indirect probes, such as Drell-Yan angular coefficient (\( A_i \)) measurements, provide valuable insights into the electroweak sector and Quantum Chromodynamics (QCD). These measurements study the angular distributions of leptons produced in the Drell-Yan process, decomposing the differential cross-section into angular coefficients (\( A_i \)), which encapsulate key aspects of the underlying dynamics. While these coefficients have been measured extensively for Z boson production, similar measurements for W bosons pose significant challenges due to substantial background contributions and the neutrino from W decays, which complicates the reconstruction of the W boson’s rest frame.
This thesis presents methodologies to overcome these challenges using 338.1 inverse picobarns of low-pileup data at a center-of-mass energy of 13 TeV from the ATLAS experiment at CERN. By optimizing kinematic selection to probe the Lam-Tung relation, particularly in regions of high transverse lepton momentum, the analysis faced an increase in fake backgrounds. This challenge necessitated sophisticated estimation methods using complex three-dimensional binning techniques. Despite persistent difficulties in controlling backgrounds and achieving data fit convergence, this work establishes a strong foundation for future precise measurements and exploration of \( W \)-\( A_i \) coefficients.
”The W boson production at ATLAS experiment: Drell-Yan angular distributions for probing hard QCD” (pdf)
The PhD defense will take place at the Aula of the Radboud Universiteit Nijmegen, Comeniuslaan 2, Nijmegen
More information and a link to the livestream on the website of the Radboud University
Supervisors: prof. dr. N. de Groot en prof. dr. A. Romaniouk
contact: Daniil Ponomarenko